Wound body for use as an ammunition shell

ABSTRACT

According to known techniques for winding an ammunition shell the number of thread layers is often reinforced as compared to the remaining part of the shell wall, especially in those zones of the shell where the load is the highest, thereby, however, inevitably increasing the thickness of the shell wall. If the space for the propelling charge in the wound shell is to be enlarged while the outer geometry of the wound shell remains the same, that is with the same space provided in the weapon for the charge, the wall thickness has to be reduced. In order to provide the shell with the same mechanical stability, despite the reduction in wall thickness, as shells whose wall thickness is not reduced, the wound body of the shell ( 50 ) is produced from chemical fibers ( 53 ), preferably from synthetic and inorganic chemical fibers.

[0001] The invention relates to a casing for ammunition, the wall of thecasing comprising a combustible or consumable wound body.

[0002] DE 198 49 824 A1 discloses a casing for ammunition in which thewall comprises a combustible or consumable wound body having at leastone double layer of crossing threads. The threads are deposited unevenlyover the length of the wound body. The winding density, i.e. the numberof times the thread(s) is/are deposited over the length of the woundbody, is matched to the actual and possible loads and the desiredcombustion behaviour. For example, the higher the pressure load on acasing in one region, the greater the number of thread layers selectedin this region.

[0003] A winding technique of this type results in the number of threadlayers, particularly in the regions of the casing in which the load isgreatest, being greater than the number of thread layers in theremaining part of the casing wall. However, a greater number of threadlayers must also result in a thicker casing wall.

[0004] However, if the aim is to increase the area for the propellantcharge in the wound casing whilst maintaining the same external geometryof wound casing, i.e. the same charge area of the weapon, it isnecessary to reduce the wall thickness. Whilst, with a large wallthickness, it is advantageous to use a thread which has a low tensilestrength and yet ensures good combustibility or consumability, forexample viscose threads, the threads which are generally used do notenable the required mechanical strength of the casing to be achievedwhen the wall thickness is reduced and the pressure and temperatureloads are consequently increased.

[0005] An object of the present invention, therefore, is to maintain thestrength values of the casing wall with the same external diameter,despite having a smaller wall thickness.

[0006] This object is achieved with the aid of the characterisingfeatures of the first claim. Advantageous embodiments of the inventionare claimed in the subclaims.

[0007] According to the invention, the wound body of the casing is madefrom man-made fibres, preferably synthetic chemical fibres such aspolyamide and polyester, and inorganic chemical fibres such as silicatefibres (glass fibres) or carbon fibres. With yarns made from man-madefibres, it is possible to differentiate between monofilament yarns, i.e.filament yarns which are spun from single-hole nozzles and comprise asingle thread or a single fibre, and multifilament or polyfilament yarnswhich are spun from, or composed of, a plurality of threads or fibres.The fibres can also be connected together in a random arrangement toform a non-woven such fibres having a predetermined limited length.

[0008] The tensile strength of the fibres used according to theinvention is substantially greater than that of fibres made from naturalstarting materials. For example, the tensile strength of glass fibres asmeasured in the direction of the fibre is greater than that of steel andis approximately 2500 N/mm². The tensile strength of carbon fibres, forexample, is between 1500 N/mm² and 3500 N/mm².

[0009] Of the plastics fibres, aramide fibres having a tensile strengthof approximately 2000 N/mm² are particularly suitable. In addition to ahigh modulus of elasticity, fabrics made from aramide fibres also haveextreme impact resistance. The modulus of elasticity of these fibres isapproximately 130×10³ N/mm².

[0010] In a further embodiment of the invention, it is also possible forthe wound body to be wound from a blend of threads each made from one ofthe named fibre types. Here, at least two threads of different fibretypes can be deposited in a parallel arrangement next to one another inone layer of the wound body. This is possible both when the threads aredeposited in parallel on the circumference of the wound body and whenthe threads are deposited so as to be cross-laid. In order to match thewall thickness of the wound body and its strength in optimum manner, itis thus advantageously possible to use threads of a material having arelatively high tensile strength in those areas where the casing is alsosubjected to relatively high loads.

[0011] The wound body can also be composed of fabric strips instead ofindividual wound threads. This is advantageous in that the casing wallis wound more easily. Moreover, if a thread tears, there is no risk of aweak point appearing within the casing wall, as occurs at the tear pointof individual threads. Furthermore, the winding procedure is completedmore quickly. In contrast to depositing individual threads, the windingof fabric is furthermore advantageous in that a fabric strip can beapplied to the wound body with a more even stress distribution than oneindividual thread or a plurality of individual threads next to oneanother.

[0012] Since, when there is pressure in a cylinder, the forces actingtangentially on the circumference of the cylinder are greater than theforces acting on the cylinder wall in the longitudinal direction, it isadvantageous for the threads of a fabric which extend substantially inthe circumferential direction of the casing to have a higher tensilestrength than threads arranged substantially in the longitudinaldirection of the casing. It is known that a fabric generally compriseslongitudinally extending warp threads and transversely extending weftthreads. When winding a fabric, it is useful with reference to thestability of the fabric, for the warp threads to be wound about thecasing axis and the weft threads to extend substantially in thelongitudinal direction of the casing, for the reasons described above,it is therefore advantageous for the warp threads to be made from amaterial which has a higher tensile strength than that of the weftthreads.

[0013] Different fibre types can be processed to form so-called blendedor hybrid fabrics. It is thus possible to combine the differentproperties of the individual fibres in one component. If, for example,carbon and aramide fibres are combined in one fabric, the wound bodywhich is manufactured therefrom and provided with a binding agent isless rigid than a wound body manufactured purely from plastics fibres,and yet has a substantially greater impact resistance.

[0014] The properties of a wound body of fabric are furthermoreinfluenced by the thread density and the fabric weave. A fabric in plainweave has a smaller float (narrower curvature) of the threads than afabric in atlas weave. A greater float results in improved drapabilityand strength of the wound body as a result of the improved stretch ofthe threads.

[0015] In a further embodiment of the invention, the wound body cancomprise at least one layer of a non-woven fabric. A non-woven fabricdoes not comprise threads but individual fibres of a particular lengthwhich are generally oriented irregularly in the non-woven fabric. Anon-woven fabric is essentially less strong than a woven fabricalthough, by selecting the fibres and their arrangement in the non-wovenfabric accordingly, this latter can be given such a strength that itsuitable for a winding procedure. Unlike a woven fabric, a non-wovenfabric has the advantage of being able to absorb a substantially greatervolume of liquid substances than a woven fabric. By means of a non-wovenfabric, it is thus possible to introduce substances into the wound bodywhich produce propellant gases upon their combustion in addition to thecharge.

[0016] The strength and cohesion of the wound body is substantiallyproduced by the binding agents, which are either added to the fabric orthe non-woven fabric in known manner before the threads are wound, orwith which the wound body is saturated after it has been produced. It isalso possible to admix an explosive substance with the binding agent inknown manner, so that the combustion or consumption of the wound casingis accelerated and additional propellant gases for the projectile areproduced. It is already known that the porosity of the thread layers ofa fabric influences the combustion or consumption at a wound casing.

[0017] Whereas with a wound body manufactured by winding threads, aswith a woven fabric, there are spaces between the threads which may beperceived as pores, in the case of a non-woven fabric, pores are notperceivable in such an obvious form. The alignment of the fibres, theirlength and also the curl are criteria which determine the density of anon-woven fabric and therefore its capacity for receiving fillingmaterials.

[0018] Since the non-woven fabric essentially has no open pores, it isparticularly suitable not only for absorbing liquid substances but alsofor fixing during the winding procedure substances which are introducedinto the winding gap between an already-wound non-woven fabric layer andthe non-woven fabric layer to be wound. It is not necessary here toapply these substances in liquid form. Their consistency must only besuch that they can be fixed between the two non-woven fabric layersduring the winding procedure.

[0019] The invention is explained in more detail with reference toexemplifying embodiments.

[0020] As an example of fabric weaves, there is shown:

[0021]FIG. 1 a plain weave

[0022] a) in plan view

[0023] b) in section

[0024]FIG. 2 a twill weave

[0025] a) in plan view

[0026] b) in section

[0027]FIG. 3 an atlas weave

[0028] a) in plan view

[0029] b) in section

[0030]FIG. 4 an example of a blended fabric

[0031]FIG. 5 an example of a hybrid fabric and

[0032]FIG. 6 an example of a casing the wound body of which has beenwound from layers of non-woven fabric.

[0033] View a) of FIG. 1 shows a plan view of a fabric 1 in plain weave.The plan view of the differently coloured warp and weft thread shows thetypical chequered pattern of a plain weave. The threads 2 shown in darkand also the threads 3 shown in light alternate continuously in terms oftheir crossing points 4. Between the individual threads, pores 5 remainwhich can he filled with binding agents or possibly binding agents withadded explosive substances. However, they can also be used as air poresin order to provide the necessary combustion air for combustion.

[0034] The section through the fabric 1 illustrated in FIG. 1 b) showsthe typical thread course with the strong curvature, float, of thethreads determined by the weave.

[0035]FIG. 2 a) shows a plan view of a fabric 10 in a so-called twillweave. This type of weave has a diagonal course of crossing points 4 orthe threads 3 and 4.

[0036] The section through the fabric 10 illustrated in FIG. 2 b) showsthat the float, the curvature of the threads, is wider and the threadsthus have a greater stretch.

[0037] The threads in the fabric 20 having the atlas weave illustratedin FIG. 3 have an even greater stretch. An atlas weave is produced bythe regular distribution of the upward and downward course of the warpthread over the entire weave repeat, so that they do not come intocontact at any point. This produces a smooth fabric surface. To thisend, at least 5 warp and weft threads are required for each repeat. Therepeat is the unit of repetition for a particular thread crossing, orthe same figure in the case of patterned textiles or wallpapers. As theplan view of the fabric 20 shows, a crossing point 4 is located only atthe intersection with every fourth thread.

[0038]FIGS. 4 and 5 show two fabrics which are woven with threads ofdifferent fibre materials.

[0039]FIG. 4 shows a blended fabric 30 in a plain weave, in which forexample the threads 32 extending in the illustrated X-direction are madefrom carbon fibres, and the threads 31 extending in the Y-direction aremade from glass fibres.

[0040]FIG. 5 shows a so-called hybrid fabric 40. The threads ofdifferent fibres alternate both in the X-direction and the Y-direction.Thus, a thread made from carbon fibres 42 lies next to each thread madefrom aramide fibres 41.

[0041] In the case of blended fabrics and in the case of hybrid fabrics,it is possible to combine the different properties of the individualfibres in one component.

[0042]FIG. 6 shows a casing 50 whose wall 51 comprises three layers 52of a width of non-woven fabric 53 which are wound over one another. Thiswidth of non-woven fabric is wound about the axis 53 in three layer 52with an angle of twist 54. In addition to the bind agent, the non-wovenfabric 53 itself can be saturated with explosive substances to promotecombustion or consumption.

[0043] During the winding procedure, when winding onto thealready-present first non-woven fabric layer, it is also possible tointroduce a substance between the already-wound non-woven fabric layerand the non-woven fabric layer to be wound. It can also support theweave between the non-woven fabric layers 52. It may also have explosivesubstances of a different composition, such as that, for example, whichis present in the substance with which the non-woven fabric 53 itself issaturated.

1. A casing for ammunition, the wall of the casing comprising acombustible or consumable wound body, characterised in that the woundbody of the casing is made front man-made fibres, preferably syntheticand inorganic chemical fibres (2, 3; 31, 32; 41).
 2. A casing accordingto claim 1, characterised in that the wound body comprises a blend ofthreads (31, 32; 41, 42) each made from a different fibre type.
 3. Acasing according to claim 1 or 2, characterised in that the threadshaving a higher tensile strength are deposited on the wound body in thedirection of the higher load.
 4. A casing according to one of claims 1to 3, characterised in that at least two threads of different fibretypes are deposited in a parallel arrangement next to one another in onelayer of the wound body.
 5. A casing according to one of claims 1 to 3,characterised in that the wound body is made from woven fabric strips(1, 10, 20,30, 40).
 6. A casing according to claim 5, characterised inthat the warp heads and the weft threads of the woven fabric (30; 40)comprise threads (31, 32; 41, 42) of different fibre types.
 7. A casingaccording to claim 5 or 6, characterised in that the threads (32) of awoven fabric (30) which extend substantially in the circumferentialdirection (x) of the casing have a higher tensile strength than thethreads (31) arranged substantially in the longitudinal direction (y) ofthe casing.
 8. A casing according to one of claim 5 to 7, characterisedin that the fabrics (1, 10, 20, 30, 40) have different thread weaves. 9.A casing according to one of claims 1 to 3, characterised in that thewound body (50) comprises at least one layer (52) of a non-woven fabric(53).
 10. A casing according to one of claims 1 to 9, characterised inthat the threads (2, 3; 31, 32; 41, 42) or fibres (53) of the wound bodyare saturated with a binding agent.
 11. A casing according to claim 10,characterised in that an explosive substance is admixed with the bindingagent.
 12. A casing according to one of claims 9 to 11, characterised inthat a combustion-controlling substance (56) is additionally embeddedbetween the layers (52) of the non-woven fabric (53).
 13. A casingaccording to claim 12, characterised in that the substance (56) embeddedbetween the layers (52) of the non-woven fabric (53) has a compositionwhich is chemically different from that of the binding agent or theexplosive substance with which the non-woven fabric (53) is saturated.